Production of phosphorus



Patented July 12, 1932 UNITED STATES PATENT emce- ROTHE wEIeEL', F NASHVILLE, TENNESSEE, nss elvon'ro vIc'ro oHEMIcAL WORK-8,:

A CORPORATIONOE ILEINoIs. V I

PRODUCTION OF PIHIOSPHORUS No Drawing.

The present invention relates to improvements in the production of phosphorus and phosphorus compounds by volatilization processes, and more particularly to the production of phosphorus and phosphorus compounds from natural phosphate minerals in the blast furnace processes.

It has hitherto been proposed, in the production of phosphorus and phosphorus compounds, to grind the natural phosphate min eral, for example, a phosphate rock and form it into briquettes with carbonaceous material and silicious material, the carbonaceous material being provided in a proportion-such as to give the resulting briquetted mass a 'carbon content substantially in excess of that theoretically required in the reduction reaction and the proportion of silicious material being such as to provide all or at least part of that necessary for the reaction. In carrying out the operation in the blast furnace, the briquettes thus produced have beencharged into the furnace, together with coke in sufficient quantity to provide the fuel requirements for the operation of the furnace with usually some excess thereover and, when necessary, additional silicious material for the reaction, suitably in the form of silica pebbleQ In operating in this manner, for exam ple, the ratio of the fuel coke supplied relative to the briquettes and silica has ordinarily varied, say from 0.730 1 to 0.750 1. By employing the ground phosphate mineral in briquetted form, it is possible to employ runof-mine and fine phosphate rock and other phosphate minerals and to secure a uniform I composition of feed.

It has now been found that a marked improvement in operating conditions of a volatilization furnace operating upon a briquetted charge may be effected by reducing the content of carbonaceous material incorporated in the briquettes with the phosphate rock or other phosphate mineral to substantially less than that required theoretically in inthe reduction reaction, and preferably to form 25 to 75% of the theoretical proportion. The proportion of carbon to P 0 theoretically required for the reaction is 0.422 1, and in operatingin accordance with the present in- Application filed June 8, 1931. Serial No. 543,028.

'vention, it is preferred to reduce its ratio substantially,preferably to not higher than 0.306: 1. In atypical operation, I have employed a ratio of carbon to'P O of approximately 0.153:1.

The following exampleillustrates an operation in accordance withthe persent invention, it being understood, however, that the scope of the invention is not limited by the specific details of the example as herein set forth.

The phosphate rock employed is a run-ofmine rock showing, on the usual proximate analysis, 3.35% moisture; 25.03% P 0 and 33.65% CaO. The phosphate rock is ground to'suitable fineness say, below mesh and preferably from -4O mesh, and is formed into briquettes with the desired carbonaceous material, for example, bituminouscoal,

the siliciousmaterial in the desired proportions (or if a highly silicious-phosphate rock is used, extra silicious material maybe omitted), a suitable organic binder such as sulfite liquor, molasses or the like being employed. After briquetting, the briquettes are" dried. In the case of the phosphate rock above described,-which has a high silica content, the briquettesmay be formed from a mixture containing 92.25% of the phosphate rock, 6% of coal and 1.75% of a sulflte liquor containing 50% solids. The coal employed fcontains. about 62% carbon and the briquettes produced, after drying, have the following composition:

Moisture 0.99% P 0 24.29% S10 21.62% CaO 32.41% Carbon 3.71%

rated directly in the briquettes or that in the briquettes together with the added silica, is calculated as in ordinary blast furnace practice to give a readily fusible fluid slag; for example, to maintain a ratio of SiO to GaO of 0.8:1, or suitably withinthe range of from 0.6: 1 to 1.2: 1.- With briquettes "of the constant average composition'above set forth, in a typicaloperation, the ratio of briquettes and added silicious material to fuel coke may be in the proportion of 100 parts of briquettes and 1 parts of added silica to 70.3 parts of coke. It will be understood, of course, that the silicious material may be incorporated in the briquettes if desired, and that the proportions of the various constituents will vary, as inordinary blast furnace practice, in accordance with the operating conditions desired andthe relative proportions of lime to proportion of fuel coke orcarbonaceous material extraneousto the briquettes required for the operation of'the furnace, which is controlled to secure the desired hearth temperature, is not increased; on the contrary, it has been found that it may be reduced as much as 4 to8% or even 10%. 'The desired high liberation and volatilization of the phosphorhearth temperatures,-say about 1600 O. are

more easily maintained, with a more effective us, an increased yield, and areduction of the phosphate content ofthe slag. Particularly marked are the reductions in quantity of very fine flue dust or fume carried by the gases from the blast furnace and the reduction in 'accumulationsof infusible material material be incorporated inthe briquettes of in the hearthzone of the furnace. 3 I In carrying out the present invention, 1s found desirable that some carbonaceous constant average composition which are used in charging the furnace, 1n proportion at least 15% of the theoretical requirements,

based upon the P 0 present. While coke may be employed forthe purpose, it is preferredithata carbonaceous material containing volatlhzable hydrocarbons be employed,

such as anthracite coal or preferably bituminous coal, the proportion of the carbonaceous material being such as to provide the desired quantity of fixed carbon in the briquette. It 1s preferred that the proportion of carbon incorporated in the briquettes shall not exceed 7 5% of the theoretical, and ingeneral 30 to bonaceous 10% of the theoretical requirements is employed.

I claim: a 1. The method of producing phosphorus in a volatilization furnace which comprises commingling with a proportion of carbonaceous material less than that required for reduction of its phosphorus content and forming coherent briquettes of constant average composition therefrom, charging such briquettes into the furnace to pass into the volatilization zone therein, and maintaining a temperature in said furnace to liberate phosphorusand form a molten slag.

2. The method of producing phosphorus in a volatilization furnace which comprises COHl: mingling phosphorus-containing mineral,

"silicious material, and a proportion of carbonaceous material less than that required for reduction of the phosphorus content of the mineral, forming coherent briquettes of constant average composition from the mixture, and charging such briquettes with additional carbonaceous material into the furnace to pass into the volatilization zone there in, and maintaining a temperature in said furnace to liberate phosphorus and'form'a molten slag. s

' 3. The method ofproducing phosphorus in a blastfurnace whichcomprises commingling ground phosphate mineral and silicious material with carbonaceous material in proportion substantially less than that required for reduction of the phosphorus, forming co-' herent briquettes of the mixture, and charging such briquettes into the furnace with added carbonaceous material required to maintain, by combustion, the desired temperature in the furnace, and maintaining a temperature in the furnace by combustion of said fuel to liberate phosphorus and form a molten slag. V

4'. The method of producing phosphorus in a blast furnace which comprises comphosphorus-containing mineral mingling ground phosphate rock with car 7 material containing volatile hydrocarbon constituents, the proportion of carbonaceous material being less than that required for reduction of the phosphorus, forming coherent briquettes of themixture, charging said briquettes together with-carbon for fuel into the furnace to pass therethrough, and maintaining a temperature in the furnace by combustion of said fuel car bon to liberate phosphorus and form a molten slag.

5. The method of producing phosphorus in a blast furnace which comprises commingling ground phosphate rock with carbonaceous materialin a proportion from 15 to 75% of that required for reduction of the phosphorus, forming briquettes of said mixture, charging such briquettes into the furnace together with carbonaceous material in amount required for fuel and supplying silicious material in the furnace in proportion to supply the requirements for slag of desired composition, said materials passing through the furnace, and maintaining a temperature in the furnace by combustion of the carbonaceous material therein to liberate phosphorus and form a molten slag.

6. The method ofproducing phosphorus in a blast furnace which comprises commingling ground phosphate rock with carbonaceous material in a proportion from 30 to 410% of that required for reduction of the phosphorus, forming briquettes of said mixture, charging such briquettes into the furnace together with carbonaceous material in amount required for fuel and supplying prising phosphate mineral and carbonaceous material containing volatile hydrocarbon constituents, said carbonaceous material being present in proportion to supply carbon to the extent of 15 to 75% of that required for reduction of the phosphorus of the mineral.

9. A briquette for use in a phosphorus volatilization furnace, said briquette comprising phosphate mineral and carbonaceous material containing volatile hydrocarbon constituents, said carbonaceous material being present in proportion to supply carbon to the extent of 30 to 40% of that required for reduction of the phosphorus of the mineral.

ROTHE WEIGEL. 

